Using a sharp knife, lightly score both sides of the flank steaks in a crisscross pattern. Place steaks in a large, resealable plastic storage bag.
In a medium-sized mixing bowl, combine teriyaki sauce, cola, onion, garlic, red wine vinegar, oil, hot sauce and salt and pepper. Whisk well until mixed. Reserve ½ cup of marinade for later. Pour the remaining marinade into the bag with the steaks. Seal the bag and gently shake to cover all the steaks. Refrigerate for 2 hours
Preheat broiler on your stove.
Remove steaks from refrigerator. Place them on a broiler pan or a pan with a rack on it. Broil for 10 to 12 minutes on each side. (Note: Flank steak should be cooked thoroughly to prevent chewiness. Aim for medium to medium-well temperature. Not rare!)
Remove steaks from oven and let them rest for 10 minutes.
Cut steaks into thin slices. Pour the reserved marinade over the steaks or use it as a dipping sauce.